偷点春光

春寒料峭,严冬的余韵还在悠悠地飘着,寒冷而枯燥。＂不如去找春天吧!＂我对姐姐说。她欣然答应。街上的光景并不热闹,光秃秃的树木,万点绿中竟无半朵鲜花,单调且乏味,好像还没有来到春天。我有些后悔这莽撞的提议了,踌躇的脚步,吞吐的话语,无不是我失意的展示。我就这样,百无聊赖地踢着石子儿,拉着姐姐的手。

Pseudo-dynamic analysis of overturning stability of retaining wall

A new method was presented to determine the safety factor of wall stability against overturning based on pseudo-dynamic approach. In this time-dependent method, the actual dynamic effect with variation of time and propagation of shear and primary wave velocities through the backfills was considered. Planar failure surface was considered behind the retaining wall. The results were compared with those obtained from Mononobe-Okabe theory. It is found that there is a higher value of safety factor by the present dynamic analysis. The effects of wall inclination, wall friction angle, soil friction angle and horizontal and vertical seismic coefficients on the overturning stability of retaining wall were investigated. The parametric study shows that both horizontal and vertical seismic accelerations have decreasing effect on the overturning stability of retaining wall.

Attributional Styles in Adolescents with Transfusion-dependent Thalassemia

This study focused on the way that Adolescents with Transfusion- dependent thalassemia explained negative or positive events in their life （Attributional Styles）. It is defined by three dimensions describing the cognitive appraisal of the events： internal-external, stable-unstable, and global-specific. With cross-sectional research design, the observations consist of 102 adolescents （48 males, 54 females） who diagnosed with Transfusion-dependent thalassemia （more than 50 times for blood transfusions） completed the measure of Attributional Styles and Anxiety Questionnaires. The correlations in the predicted directions among variables examine with Pearson product-moment correlation coefficients, t-test, and One-way ANOVA to ascertain a significant between the group differences on attributional factors and levels of anxiety symptoms. The results show that Adolescent samples with higher levels of anxiety revealed statistically significant relationship among three negative attributional dimensions （overall composite F = 4.5, p 〈 0.05; negative composite F = 4.99, p 〈 0.01; negative-internality F = 4.99 p 〈 0.01; negative-stability F = 3.42, p 〈 0.05 and negative-globality F = 3.77, p 〈 0.05）. In addition, significant age- group differences were found for the total negative-globality （t = 2.05, p 〈 0.05） and negative- globality （t = -2.22, p 〈 0.05）. These data are consistent with the reformulated learned helplessness model of depression. In finding, the individuals who attribute negative life events to internal, stable, and global causes will be more vulnerable to anxiety than those who make external, unstable, and specific attributions. Most interestingly, those adolescents more than 17 years evidence more negative-globality attfibutional style than group less than 16 years, and female adolescents may influence this pattern. These results suggest that targeting Adolescents with Transfusion-dependent thalassemia may be important for improving aspect of coping on psychological adjustment to their chronic illness.

Numerical Simulation of Seawater Intrusion from Estuary into River Using a Coupled Modeling System

One of the most important causes of the freshwater shortage in estuarine area is the increasing seawater intrusion into the river.To simulate seawater intrusion properly,two important factors should be considered.One is the bidirectional and time-dependent coupling effects between river discharges and tidal forces.The other is the three-dimensional and stratified structure of dynamic processes involved.However,these two factors have rarely been investigated simultaneously,or they were often simplified in previous researches,especially for the estuary connected with an upstream river network through multiple outlets such as the Pearl River Estuary(PRE).In order to consider these two factors,a numerical modeling system,which couples a one-dimensional river network model with a three-dimensional unstructured-grid Finite-Volume Coastal Ocean Model(FVCOM),has been developed and successfully applied to the simulation of seawater intrusion into rivers emptying into the PRE.By treating the river network with a one-dimensional model,computational efficiency has been improved.With coupling 1D and 3D models,the specification of upstream boundary conditions becomes more convenient.Simulated results are compared with field measured data.Good agreement indicates that the modeling system may correctly capture the physical processes of seawater intrusion into rivers.

Drought adaptability of phreatophytes:insight from vertical root distribution in drylands of China

Aims The vertical distribution of plant roots is a comprehensive result of plant adaptation to the environment.Limited knowledge on fine vertical root distributions and complex interactions between roots and environmental variables hinders our ability to reliably predict climatic impacts on vegetation dynamics.This study attempts to understand the drought adaptability of plants in arid areas from the perspective of the relationship between vertical root distribution and surroundings.Methods By analyzing root profiles compiled from published studies,the root vertical profiles of two typical phreatophytes,Tamarix ramosissima and Populus euphratica,and their relationships with environmental factors were investigated.A conceptual model was adopted to link the parameter distribution frequency with plant drought adaptability.Important Findings The strong hydrotropism(groundwater-dependent)and flexible water-use strategy of T.ramosissima and P.euphratica help both species survive in hyperarid climates.The differences in the developmental environments between T.ramosissima and P.euphratica can be explained well by the different distribution characteristics of root profiles.That is,higher root plasticity helps T.ramosissima develop a more efficient water-use strategy and therefore survive in more diverse climatic and soil conditions than P.euphratica.We conclude that the higher variation in root profile characteristics of phreatophytes can have greater root adaptability to the surroundings and thus wider hydrological niches and stronger ecological resilience.The inadequacy of models in describing root plasticity limits the accuracy of predicting the future response of vegetation to climate change,which calls for developing process-based dynamic root schemes in Earth system models.

Asymptotics for partly linear regression with dependent samples and ARCH errors:consistency with rates

Partly linear regression model is useful in practice, but littleis investigated in the literature to adapt it to the real data which are dependent and conditionally heteroscedastic. In this paper, the estimators of the regression components are constructed via local polynomial fitting and the large sample properties are explored. Under certain mild regularities, the conditions are obtained to ensure that the estimators of the nonparametric component and its derivatives are consistent up to the convergence rates which are optimal in the i.i.d. case, and the estimator of the parametric component is root-n consistent with the same rate as for parametric model. The technique adopted in the proof differs from that used and corrects the errors in the reference by Hamilton and Truong under i.i.d. samples.

Scale dependency of Liolaemus lizards＇ home range in response to different environmental variables

Animal habitat-use patterns cannot be isolated from scale issues. Consequently, multi-scale studies provide a complete characterization of ecological patterns that can further explain the observed variation. Liolaemus constitutes the world＇s second most speciose lizard genus. In this study, we assessed the relationships between home range size and environmental variables at 3 different spatial scales. The study at a local and regional scale was focused on the habitat specialist Liolaemus multimaculatus. The lizard＇s home range was calculated using the minimum convex polygon method in populations from grassland sites of the coastal sand dunes of the Argentinean Pampas under 2 different conditions, with or without forestations of Acacia Iongifolia. On the other hand, at a geographical scale we considered the evolutionary implications of 20 species of Liolaemus. Home range size, phylogeny, ecological, environmental, and climatic data were ob- tained from the literature and remote sensing. L. multimaculatus home range varied from 12.66 to 570.00 m. Regionally, this species had smaller home ranges in forested habitats （X： 94.02 m2） com- pared with the non-forested sites （X： 219.78m2）. Habitat structure, vegetation types, and food availability would explain the space use at finer scales. When the 20 species of Liolaernus were considered, high mean air temperature and broad thermal amplitudes showed an inverse relationship with home range size. Neither net primary productivity nor phylogeny was good predictors for home range variation at geographical scale. This study highlights the scale dependence of the explicative capability of a set of environmental and intrinsic variables on home range patterns.

Frequency-dependent rupture process,stress change,and seismogenic mechanism of the 25 April 2015 Nepal Gorkha M_w 7.8 earthquake

On 25 April 2015,an M_w 7.8 earthquake occurred on the Main Himalaya Thrust fault with a dip angle of^7° about77 km northwest of Kathmandu,Nepal.This Nepal Gorkha event is the largest one on the Himalayan thrust belt since 1950.Here we use the compressive sensing method in the frequency domain to track the seismic radiation and rupture process of this event using teleseismic P waves recorded by array stations in North America.We also compute the distribution of static shear stress changes on the fault plane from a coseismic slip model.Our results indicate a dominant east-southeastward unilateral rupture process from the epicenter with an average rupture speed of ~3 km s^(-1).Coseismic radiation of this earthquake shows clear frequency-dependent features.The lower frequency(0.05-0.3 Hz) radiation mainly originates from large coseismic slip regions with negative coseismic shear stress changes.In comparison,higher frequency(0.3-0.6 Hz) radiation appears to be from the down-dip part around the margin of large slip areas,which has been loaded and presents positive coseismic shear stress changes.We propose an asperity model to interpret this Nepal earthquake sequence and compare the frequency-dependent coseismic radiation with that in subduction zones.Such frequency-dependent radiation indicates the depth-varying frictional properties on the plate interface of the Nepal section in the main Himalaya thrust system,similar to previous findings in oceanic subduction zones.Our findings provide further evidence of the spatial correlation between changes of static stress status on the fault plane and the observed frequency-dependent coseismic radiation during large earthquakes.Our results show that the frequency-dependent coseismic radiation is not only found for megathrust earthquakes in the oceanic subduction environment,but also holds true for thrust events in the continental collision zone.

Identification of hydraulic conductivity distributions in density dependent flow fields of submarine groundwater discharge modeling using adjoint-state sensitivities

A mathematical optimal control method is developed to identify a hydraulic conductivity distribution in a density dependent flow field. Using a variational method, the adjoint partial differential equations are obtained for the density-dependent state equations used for the saline aquifer water flow. The adjoint equations are numerically solved in through a finite difference method. The developed method is applied to identify the hydraulic conductivity distribution through the numerical solution of an optimal control problem. To demonstrate the effectiveness of the optimal control method, three numerical experiments are conducted with artificial observation data. The results indicate that the developed method has the potential to accurately identify the hydraulic conductivity distribution in a saline water aquifer flow system.